Obsessive-compulsive disorder (OCD) is a type of anxiety disorder where an individual has unreasonable thoughts and fears (obsessions) that lead to engaging in repetitive behaviors (compulsions). The brain gets stuck on a particular thought or urge and just can't let go. Worries, doubts, and superstitious beliefs are common in everyday life. But with obsessive-compulsive disorder, the obsessions aren't reasonable and there may be efforts to ignore them or stop them. But that only increases the distress and anxiety. The individual then feels driven to perform compulsive acts in an effort to ease distress. Obsessive-compulsive disorder often centers around themes, such as a fear of getting contaminated by germs. A person with OCD may sometimes have one or the other. Common obsessions are: contamination fears of germs, dirt, etc., imagining having harmed oneself or others, imagining losing control or having aggressive urges, intrusive sexual thoughts or urges, excessive religious or moral doubt, forbidden thoughts, a need to have things "just so," and a need to tell, ask, or confess. Common compulsions are: washing, repeating, checking, touching, and counting. A person with contamination fears, for example, may compulsively wash his hands until they're sore and chapped.Despite efforts to stop the thoughts or behaviors, the distressing thoughts of obsessive-compulsive disorder keep coming back. A person may repeatedly check that she has turned off the stove or iron because of an obsessive fear of burning the house down. She may have to count certain objects over and over because of an obsession about losing them. Unlike compulsive drinking or gambling, OCD leads to more ritualistic behavior — and a vicious cycle that's characteristic of obsessive-compulsive disorder. When these compulsions become excessive (such as hours of hand washing or driving around and around the block to check that an accident didn't occur) then a diagnosis of OCD is made.

Before the arrival of modern medications and cognitive behavior therapy, OCD was generally thought to be untreatable. Most people with OCD continued to suffer, despite years of ineffective psychotherapy. Today treatment can help most people with OCD. OCD symptoms tend to wax and wane over time. Some may be little more than background noise; others may produce extremely severe distress. OCD starts at any time from preschool age to adulthood (usually by age 40). One third to one half of adults with OCD report that it started during childhood. Unfortunately, OCD often goes unrecognized. On average, people with OCD see three to four doctors and spend 9 years seeking treatment before they receive a correct diagnosis. Studies find that it takes an average of 17 years from the time OCD begins for people to obtain appropriate treatment. OCD tends to be underdiagnosed and undertreated for a number of reasons. People with OCD are secretive about their symptoms or lack insight about their illness. Many healthcare providers are not familiar with the symptoms or are not trained in providing the appropriate treatments. Some people don't have access to treatment resources. This is unfortunate because earlier diagnosis and proper treatment, including finding the right medications, can help people avoid the suffering associated with OCD. This lessens the risk of developing other problems, such as depression, marital and work problems.

There may be some familial inheritance. No specific genes for OCD have been identified. Research suggests that genes do play a role in the development of the disorder. Childhood-onset OCD runs in families (sometimes in association with tic disorders). When a parent has OCD, there is a slightly increased risk that a child will develop OCD, although the risk is still low. When OCD runs in families, it is the general nature of OCD that is inherited, not specific symptoms. Thus a child may have checking rituals, while his mother washes compulsively. There is no proven cause of OCD. Research suggests that OCD involves problems in communication between the front part of the brain (the orbital cortex) and deeper structures (the basal ganglia). These brain structures use the chemical messenger serotonin. It is believed that insufficient levels of serotonin are involved in OCD. Drugs that increase the brain concentration of serotonin often help improve OCD symptoms. Pictures of the brain at work also show that the brain circuits involved in OCD return toward normal in those who improve after taking a serotonin medication or receiving cognitive-behavioral psychotherapy. Although it seems clear that reduced levels of serotonin play a role in OCD, there are no laboratory tests for OCD. The diagnosis is made based on an assessment of the person's symptoms. When OCD starts suddenly in childhood in association with strep throat, an autoimmune mechanism may be involved, and treatment with an antibiotic may prove helpful.

There are also disorders that closely resemble OCD and may respond to some of the same treatments. They include trichotillomania (compulsive hair pulling), body dysmorphic disorder (imagined ugliness), and habit disorders, such as nail biting or skin picking. While they share superficial similarities, impulse control problems, such as substance abuse, pathological gambling, or compulsive sexual activity, are probably not related to OCD in any substantial way. The most common conditions that resemble OCD are the tic disorders (Tourette's disorder and other motor and vocal tic disorders). Tics are involuntary motor behaviors (such as facial grimacing) or vocal behaviors (such as snorting) that often occur in response to a feeling of discomfort. More complex tics, like touching or tapping tics, resemble compulsions. Tics and OCD occur together much more often when the OCD or tics begin during childhood. Depression and OCD often occur in adults, and, less commonly, in children and adolescents. However, unless depression is present, people with OCD are not sad or lacking in pleasure. People who are depressed but do not have OCD rarely have the kinds of intrusive thoughts that are characteristic of OCD. Stress can make OCD worse. Although most people with OCD report that the symptoms can come and go on their own. OCD is easy to distinguish from a condition called posttraumatic stress disorder, because OCD is not caused by a terrible event. Schizophrenia, delusional disorders, and other psychotic conditions are usually easy to distinguish from OCD. Unlike psychotic individuals, people with OCD have a clear idea of what is real and what is not. OCD may worsen or cause disruptive behaviors in children and adolescents, exaggerate a pre-existing learning disorder, cause problems with attention and concentration, or interfere with learning at school. In many children with OCD, these disruptive behaviors are related to the OCD and will go away when the OCD is successfully treated. Individuals with OCD often have substance-abuse problems, as a result of attempts to self-medicate. Specific treatment for the substance abuse is usually needed. Children and adults with pervasive developmental disorders (autism, Asperger's Disorder) are extremely rigid and compulsive. They have stereotyped behaviors that often resembles very severe OCD. Those with pervasive developmental disorders have extremely severe problems relating to and communicating with other people, which do not occur in OCD.

Despite its similar name, Obsessive-Compulsive Personality Disorder (OCPD) does not involve such pathologic obsessions and compulsions, but rather is a personality pattern that involves a preoccupation with rules, schedules, and lists; perfectionism; an excessive devotion to work; rigidity; and inflexibility.

http://www.nimh.nih.gov/health/topics/obsessive-compulsive-disorder-ocd/index.shtml

http://www.mayoclinic.com/health/obsessive-compulsive-disorder/DS00189

http://www.ocfoundation.org/